There are known heretofore, as a light-emitter which emits light by stimulation from outside, phosphors for fluorescent lamps which are subject to excitation by ultraviolet light, phosphors for plasma displays, phosphors for high-speed electron excitation which are subject to excitation with electron beams, phosphors for fluorescence character-indicating tubes, phosphors for radiations excitable by a radiation such as X-rays and the like, fluorescence-regenerating phosphors excitable with heat or infrared light such as those for solid scintillators and the like, accelerated phosphors, infrared-visible conversion phosphors and others.
As for a material capable of emitting light by an external mechanical force, on the other hand, the inventors previously made proposals, in conducting preparation of a high-brightness stress light-emitting material formed from an aluminate having a non-stoichiometric composition and having lattice defects emitting light when carriers excited by mechanical energy return to the ground state or in conducting preparation of a high-brightness light-emitting material with an aluminate as the matrix substance containing, in the above matrix substance, metal ions selected from rare earth metal ions or transition metal ions as the center ions of the center of luminescence (official publication of Japanese Patent Kokai No. 2001-49251), for a method for the preparation of a high-brightness light-emitting material (official publication of Japanese Patent Kokai No. 2002-220587) characterized by comprising: mixing an aluminum alcoholate and water-soluble compounds of the ingredient metals other than aluminum in an aqueous medium followed by conversion into alkalinity so as to form a colloid, then subjecting the same to high-speed drying with addition of a dispersion-stabilizing agent to form a dried material having the dispersion-stabilizing agent deposited on the surface of the colloidal particles followed by calcination of this dried material in an oxidizing atmosphere at 500 to 900° C. and pulverizing the thus calcined material into a powder which is, before or after molding, fired in a reducing atmosphere at 1000 to 1700° C.
However, the mechanoluminescence materials known heretofore have unavoidably limited application fields in respect of their insufficient luminescence brightness and in respect of attenuation of their luminescence brightness as a stress is repeatedly applied thereto.